You can update your Odoo from Odoo-Git. Go to your Odoo folder (e.g. /opt/odoo/your_server_path) and type: git pull origin 8.0
Then restart the server with /etc/init.d/odoo-server start or stop or restart

Thanks for you answer. I followed your instructions and Odoo upgrade from version 8.0RC1 to 8.0 went smoothly, but… databases made under RC1 version of Odoo doesn’t work with the final stable version of Odoo. When I choose a database created in 8.0 RC1 version I get an ‘Intrnal Server Error’ page. Only new database made in 8.0 version works fine. In the Odoo log file can’t read any specific solution… Any idea how to use these databases in the final 8.0 Odoo version?
Please help.
Sebastian

After de update from github, please do the following: (assuming it's linux based)
Stop de odoo service
./odoo-server -d name of te database -u all.
Watch the console for errors/warnings.
Hit ctrl-c
Resart de odoo services
Hopefully it solves your problem, The command will try to make sure (upgrade) your current database which is 8.0rc1 to the 8.0 version.